Biomedical subjects

H H Lin

Publications and source records attributed to H H Lin.

At least 55 records · Page 3Linked to original sources

PubMed2000

Hepatitis C virus load during pregnancy and puerperium.

OBJECTIVE: To assess whether pregnancy and delivery influence serum levels of hepatitis C virus (HCV) in carrier mothers. DESIGN: A prospective study. SETTING: University department of obstetrics and gynaecology. PARTICIPANTS: Ten pregnant HCV carriers (group A) and 8 nonpregnant HCV carriers (group B). METHODS: Serum samples were collected for group A at first and third trimesters, delivery, postpartum 1, 3, 6, 9 and 12 months, and at every three months for 1 year for group B. MAIN OUTCOME MEASURES: Each serum sample was tested for serum alanine aminotransferase (ALT), anti-HCV titre and HCV-cDNA concentration by a competitive polymerase chain reaction (PCR) with a sensitivity of 250 copies/mL serum. RESULTS: In group A, the HCV levels remained unremarkably changed during pregnancy and delivery. However, all women had decreased HCV levels 1 and 3 months after delivery. Two women had undetectable serum HCV level postpartum and thereafter. Serum ALT values in 3 women were sporadically elevated, but did not correlate with decreased serum HCV levels. Anti-HCV titres remained unchanged during the study period. In two women from group B, the serum HCV levels were undetectable during follow up. Other 6 women showed fluctuations in the serum HCV levels but all were above 250 copies/mL. Serum ALT values were normal and anti-HCV titres remained stationary in all 8 nonpregnant carriers. CONCLUSION: Serum HCV levels are decreased 1 and 3 months after delivery. This fact might suggest that puerperium is an optimal time for antiviral therapy in HCV carrier mothers.

Adult↗

PubMed2000

Salivary cellular signaling and gene regulation.

Protein tyrosine kinase and protein serine kinase activation has been implicated in the regulation of salivary cell proliferation and differentiation. Aberrant expression and alterations of certain tyrosine or serine kinases, such as Raf or erbB2, are known to trigger salivary tumor development (Li et al., 1997; Cho et al., 1999). It has been estimated that there are about 1000 to 2000 protein kinases in the mammalian genome, with 100 to 200 of them (i.e., 10%) being tyrosine kinase (Hanks and Hunter, 1995). At present, there are approximately 85 different tyrosine kinases identified in the GenBank database. Based on the relatively slow rate of discovery in the past few years, 100 is a better approximation of the total number of tyrosine kinases encoded by each mammalian genome. It is reasonable to assume that there are about 30 to 50 tyrosine kinases expressed in a given cell at a given differentiation/proliferation stage. This number is large enough to provide a characteristic tissue-specific tyrosine kinase expression profile, but small enough to be identified in a simple screening. The hope for tyrosine kinases as differentiation or proliferation markers rests with the possibility for the identification and characterization of a differentiation/proliferation stage-specific expression pattern in salivary cells. Several ligands that transmit signal through receptor tyrosine kinases and/or Ras/Raf/ERK kinases have been extensively studied in salivary cells. This review focuses mainly on the signaling pathways activated by Raf and Etk.

Animals↗

PubMed1999

Kinase activation of the non-receptor tyrosine kinase Etk/BMX alone is sufficient to transactivate STAT-mediated gene expression in salivary and lung epithelial cells.

Etk/BMX is a non-receptor protein tyrosine kinase that requires a functional phosphatidylinositol 3-kinase via the pleckstrin homology domain to be activated by cytokine. In the present study, a conditionally active form of Etk was constructed by fusing the hormone-binding domain of estrogen receptor (ER) to an amino terminus truncated form of Etk, PHDelta1-68Etk, to generate DeltaEtk:ER. In stably transfected Pa-4DeltaEtk:ER cells, the activity of DeltaEtk:ER was stimulated within minutes by the treatment of DeltaEtk:ER stimulant, estradiol, and sustained for greater than 24 h. A robust induction in the phosphorylation of signal transducers and activators of transcription (STAT) proteins, including STAT1, STAT3, and STAT5, was accompanied with DeltaEtk:ER activation. Moreover, the conditionally activated Etk stimulated STAT1- and STAT5-dependent reporter activities by approximately 160- and approximately 15-fold, respectively, however, elicited only a modest STAT3-mediated reporter activation. Qualitatively comparable results were obtained in lung A549 cells, indicating that DeltaEtk:ER inducible system could function in an analogous fashion in different epithelial cells. Furthermore, we demonstrated that Etk activation alone augmented cyclin D1 promoter/enhancer activity via its STAT5 response element in both Pa-4DeltaEtk:ER and A549 cells. Altogether, these findings support the notion that the activation of Etk kinase is sufficient to transactivate STAT-mediated gene expression. Hence, our inducible DeltaEtk:ER system represents a novel approach to investigate the biochemical events following Etk activation and to evaluate the contribution by kinase activation of Etk alone or in conjunction with other signaling pathway(s) to the ultimate biological responses.

Animals↗

PubMed1999

Measuring recent thymic emigrants in blood of normal and HIV-1-infected individuals before and after effective therapy.

The role of the thymus in HIV-1 pathogenesis remains unclear. We developed an assay to quantify the number of recent thymic emigrants in blood based on the detection of a major excisional DNA byproduct (termed alpha1 circle) of T cell receptor rearrangement. By studying 532 normal individuals, we found that alpha1 circle numbers in blood remain high for the first 10-15 yr of life, a sharp drop is seen in the late teen years, and a gradual decline occurs thereafter. Compared with age-matched uninfected control individuals, alpha1 circle numbers in HIV-1-infected adults were significantly reduced; however, there were many individuals with normal alpha1 circle numbers. In 74 individuals receiving highly active antiretroviral therapy, we found no appreciable effect on alpha1 circle numbers in those whose baseline values were already within the normal range, but significant increases were observed in those with a preexisting impairment. The increases in alpha1 circle numbers were, however, numerically insufficient to account for the rise in levels of naive T lymphocytes. Overall, it is difficult to invoke thymic regenerative failure as a generalized mechanism for CD4 lymphocyte depletion in HIV-1 infection, as alpha1 circle numbers are normal in a substantial subset of HIV-1-infected individuals.

Adolescent↗

PubMed1999

The gene expression of the amiloride-sensitive epithelial sodium channel alpha-subunit is regulated by antagonistic effects between glucocorticoid hormone and ras pathways in salivary epithelial cells.

The functional expression of the amiloride-sensitive epithelial sodium channel (ENaC) in select epithelia is critical for maintaining electrolyte and fluid homeostasis. Although ENaC activity is strictly dependent upon its alpha-subunit expression, little is known about the molecular mechanisms by which cells modulate alpha-ENaC gene expression. Previously, we have shown that salivary alpha-ENaC expression is transcriptionally repressed by the activation of Raf/extracellular signal-regulated protein kinase pathway. Here, this work further investigates the molecular mechanism(s) by which alpha-ENaC expression is regulated in salivary epithelial Pa-4 cells. A region located between -1.5 and -1.0 kilobase pairs of the alpha-ENaC 5'-flanking region is demonstrated to be indispensable for the maximal and Ras-repressible reporter expression. Deletional analyses using heterologous promoter constructs reveal that a DNA sequence between -1355 and -1269 base pairs functions as an enhancer conferring the high level of expression on reporter constructs, and this induction effect is inhibited by Ras pathway activation. Mutational analyses indicate that full induction and Ras-mediated repression require a glucocorticoid response element (GRE) located between -1323 and -1309 base pairs. The identified alpha-ENaC GRE encompassing sequence (-1334/-1306) is sufficient to confer glucocorticoid receptor/dexamethasone-dependent and Ras-repressible expression on both heterologous and homologous promoters. This report demon- strates for the first time that the cross-talk between glucocorticoid receptor and Ras/extracellular signal-regulated protein kinase signaling pathways results in an antagonistic effect at the transcriptional level to modulate alpha-ENaC expression through the identified GRE. In summary, this study presents a mechanism by which alpha-ENaC expression is regulated in salivary epithelial cells.

Animals↗

PubMed1999

Transdermal iontophoretic delivery of enoxacin from various liposome-encapsulated formulations.

The major purpose of this work was to study the effect of various liposome formulations on the iontophoretic transport of enoxacin through excised rat skin. The electrochemical stability of these liposomes was also evaluated. The encapsulation percentage of enoxacin was significantly enhanced after 6 h incubation in an electric field; whereas the fusion of liposomes was inhibited by application of electric current. The results of iontophoretic drug transport showed that the permeability of enoxacin released from liposomes was higher compared with that of free drug. The iontophoretic permeability of enoxacin released from liposomes increased with a decrease in the fatty acid chain length of the phospholipid, which may be due to the different phase transition temperatures of the phospholipids. Incorporation of charged phospholipid resulted in an alteration of the transdermal behavior of enoxacin: the iontophoretic permeation as well as the amount of enoxacin partitioned in skin was greatly reduced after incorporation of stearylamine in liposomes, which can be attributed to the competitive ion effect. The enoxacin released from stratum corneum-based liposomes showed the highest amount of enoxacin partitioned into skin depot. The results of employing cathodal iontophoresis on negative charged liposomes suggested that the liposomal vesicles or phospholipids may carry enoxacin into deeper skin strata via the follicular route.

Administration, Cutaneous↗

PubMed1999

Transdermal iontophoretic delivery of diclofenac sodium from various polymer formulations: in vitro and in vivo studies.

The objective of this study was to evaluate the in vitro and in vivo transdermal iontophoresis of various diclofenac sodium polymer formulations. The excised rat skin, human skin as well as cellulose membrane were used to examine the in vitro drug permeation whereas the microdialysis technique was used to monitor the drug concentration in vivo. Polymer solutions based on polyvinylpyrrolidone (PVP) and hydroxypropyl methylcellulose (HPMC) binary system showed higher drug permeability than that of single polymer vehicle. The effect of formulations on drug permeation through cellulose membrane was quite different from those through rat skin and human skin, which can be explained by the different permeation pathways between them. It appeared to be a membrane-controlled mechanism but not the vehicle matrix-controlled mechanism for diclofenac hydrogels when using skin as the diffusion barrier. The recovery of diclofenac sodium in the in vivo microdialysis was approximately 80-90%, indicating this technique can be used in the intradermal drug monitoring. For all the polymer formulations tested, there was a good relationship between the in vitro and in vivo drug permeation. A synergistic effect on drug permeation was observed when transdermal iontophoresis combined with the pretreatment of cardamom oil as a permeation enhancer.

Administration, Cutaneous↗

PubMed1999

Prevalence of TT virus DNA in eastern Taiwan aborigines.

We studied the prevalence of TT virus (TTV) DNA in the general population of the eastern Taiwan aborigine villages, about 11% (34 of 317). There is no association between the presence of HBsAg and TTV DNA or between the presence of HCV RNA and TTV DNA. Therefore, the infection of HBV or HCV and the presence of TTV DNA appear to be independent from each other. The association between the presence of TTV DNA and the elevated alanine aminotransferase (and/or aspartate aminotransferase) activity was also investigated. The presence of TTV DNA was not found to be correlated with abnormal liver function (P = 0.574) when age, gender, and the presence of HBsAg, HCV RNA, and HGV RNA were all considered in the assay. The sequence homology of TTV DNA fragments between different isolates from Taiwan and N22 (the clone obtained from the original prototype strain) from Japan ranged from 84 to 97%. The recombinant protein encoded by the TTV DNA fragment corresponding to the open reading frame of N22 was expressed in E. coli successfully. However, no serum response against the recombinant protein was detected.

Adolescent↗

PubMed1999

Transient apoptosis elicited by insulin in serum-starved glioma cells involves Fas/Fas-L and Bcl-2.

The expression of fas gene in glioma cells varies with growth stage. When insulin-elicited transient apoptosis of glioma cells was in progress, the expression of fas gene increased at both transcriptional and translational levels. In contrast, the expression of fas-L gene in glioma cells remained constant. Apoptosis occurred in the cells having high level of surface Fas protein. When the expression of Fas-L in U-373MG cells was suppressed by ribozyme, the insulin-elicited transient apoptosis vanished. Overexpression of Bcl-2 in U-373MG cells did not alter significantly the cell cycle progression and the expression of fas gene. However, these cells were resistant to insulin-trigged death. Therefore, insulin-elicited apoptosis involved Fas-related death signal, and which could be prevented by the protective effect of Bcl-2.

Antigens, Surface↗

PubMed1999

Bcl-2 overexpression prevents apoptosis-induced Madin-Darby canine kidney simple epithelial cyst formation.

BACKGROUND: Madin-Darby canine kidney (MDCK) cells develop into simple epithelial cell cysts when cultured in type I collagen gel. We found that MDCK cells initially grow into multilayer cell aggregates and subsequently develop central lumen that contain apoptotic cells. We hypothesized that apoptosis might be essential for the formation of MDCK cysts. METHODS: Using MDCK cells cultured in collagen gel as the experimental model, we investigated how renal cells organize to form cysts. To delineate the role of apoptosis in the process of cyst formation, MDCK cells were transfected with the bcl-2 gene. Characterization of apoptosis was studied by morphological and biochemical methods. RESULTS: Bcl-2 overexpression conferred resistance to apoptosis. Cultured in collagen gel, Bcl-2 transfectants rarely formed a simple epithelial cyst, but instead remained as a multilayer cell aggregate containing central or multiple lumens, or even developing into branching structures. CONCLUSIONS: Because Bcl-2 overexpression averts cyst cavitation, these data clearly indicate that apoptosis is an essential initial event for renal cyst formation.

Animals↗

PubMed1999

Comparison of treatment outcomes for imipramine for female genuine stress incontinence.

OBJECTIVE: To assess the efficacy of imipramine as a treatment of genuine stress incontinence and to explore the possible determining factors for treatment success and failure. DESIGN: A prospective study. SETTING: University department of obstetrics and gynaecology. PARTICIPANTS: Forty women with genuine stress incontinence were enrolled. METHODS: Each woman was treated with 25 mg imipramine three times a day for three months. MAIN OUTCOME MEASURES: Each woman had a 20-minute pad test and urodynamic study including uroflowmetry, both filling and voiding cystometry, and stress urethral pressure profile before and after treatment. RESULTS: After treatment, 35% (n = 14) were cured, 25% (n = 10) improved by > or = 50% and in the remaining 40% (n = 16) treatment failed. The efficacy of successful treatment was 60% (95% CI 44.8-75.2). The median age and parity, as well as menopausal status, showed no statistical differences between the two groups. The pre-treatment data including pad weight, functional urethral length, maximal urethral pressure, bladder compliance at urgency, bladder capacity, and average and maximal flow rates showed no statistical differences between the two groups except urethral closure pressure (P = 0.001). Besides, the functional urethral length and urethral closure pressure were significantly improved in the treatment success group. After medication, the median functional urethral length was 3 cm (intraquantile range [IQR] 2.3-3) in the treatment success group vs 2.3 cm (IQR 2-3) in the treatment failure group (P = 0.028). The urethral closure pressure was 77 cmH2O (IQR 61-105) for the treatment success group vs 40 cmH2O (IQR 34-53) in the treatment failure group (P < 0.0001). CONCLUSIONS: The efficacy of imipramine for genuine stress incontinence was 60% (95% CI 44.8-75.2). The pre-treatment high urethral closure pressure may serve as a predictor for treatment success.

Adrenergic Uptake Inhibitors↗

PubMed1999

Chitosan hydrogel as a base for transdermal delivery of berberine and its evaluation in rat skin.

Berberine is the main ingredient of Coptis spp. This study selected berberine as a model drug to design a transdermal delivery system for the treatment of cutaneous leishmaniasis. Berberine was incorporated into chitosan hydrogel to prepare ointments. The physicochemical properties of the ointments and the release profile of berberine were investigated. The results indicated that the viscosity of chitosan hydrogel increased with an increasing amount of lactic acid or EDTA. The effect of EDTA on the viscosity was greater than that of lactic acid. By differential scanning calorimetry (DSC) measurement, no interaction was found to occur between chitosan and the soluble berberine. The release rate of berberine was inversely proportional to ointment viscosity. In in vitro skin perfusion studies, only trace amounts of berberine permeated through the rat skin due to its low oil-water partition coefficient. Surfactants were used as penetration enhancers to increase the percutaneous absorption of berberine. Among the enhancers, benzalkonium chloride was found to be the most efficient. Additionally, Tween 80 could increase the loading amount of berberine in the skin.

Administration, Cutaneous↗

PubMed1999

Early detection of unilateral occlusion of duplicated uterus with ipsilateral renal anomaly in young girls: two case reports with three-dimensional sonography.

Early detection of unilateral occlusion of duplicated uterus with ipsilateral renal anomaly is very rare and difficult. We present two cases using three-dimensional (3D) sonography as a noninvasive, comprehensive and effective method in the early detection of this syndrome in the young girls. The two young, unmarried girls had irregular abdominal discomfort and pain during the recent few years. Series traditional study showed pelvic lesions, but failed to recognized the definite cause. With 3D sonography, we demonstrated the rare congenital anatomic relationships and gave the optimal management. The girls recovered soon and had uneventful OPD follow-up. Application of 3D sonography in the suspected young girls avoids unnecessary examinations and invasive interventions, decreases the morbidity and improves their quality of life.

Abnormalities, Multiple↗

PubMed1999

Once daily isepamicin treatment in complicated urinary tract infections.

Isepamicin is a new aminoglycoside, derived from gentamicin B, which is more stable than other aminoglycosides against inactivating enzymes, and is less nephrotoxic. We evaluated the efficacy and safety of a once daily isepamicin in the treatment of complicated urinary tract infections (UTIs), as compared with amikacin. During the period May, 1997, to January, 1998, a total of 52 patients with similar demographic and baseline characteristics were enrolled into a prospective, randomized, open-label, single-center trial at the Veterans General Hospital-Kaohsiung. Eleven patients were excluded for protocol violation. The remaining 41 patients were included in the efficacy analysis. Study subjects included 16 men and 25 women, with a mean age of 57.9 (range 18-95) years. Clinical improvement was noted in 100% of patients in both the isepamicin and amikacin group. No statistically significant difference was observed between the 2 groups in regard to the rapidity of defervescence, relief of dysuria and urinary frequency, and clearance of bacteriuria and pyuria. Bacteriological cure rates were 89.4% for the isepamicin group and 100% for the amikacin group. Fifteen of 25 subjects who received isepamicin and 16 of 27 subjects who received amikacin had an adverse effect, all of which were considered to be mild except for one in the amikacin group, who had an adverse event of moderate severity (vomiting). Seven (3 isepamicin and 4 amikacin) adverse events were considered probably or possibly related to the study drug, which included eosinophilia (2 isepamicin), liver function impairment (1 isepamicin, 2 amikacin), renal function impairment (1 amikacin) and flushed face (1 amikacin). However, none of the patients had a life-threatening or severe adverse event that required discontinuation of the drug. These results show that once daily administration of isepamicin is as effective and safe as amikacin in treatment of complicated UTIs.

Adolescent↗

PubMed1998

Ethyl isopropylamiloride downregulates Na,K-ATPase gene expression which confers cytotoxicity in primary proximal tubule cell cultures.

Our original attempt was to examine whether inhibition of Na/H exchange in proximal tubule would affect the expression of basolateral membrane protein Na,K-ATPase. Three amiloride analogues were tested within the range of 10(-6) M to 10(-4) M in primary cultures of proximal tubule cells. Only ethylisopropyl amiloride (EIPA) dose-dependently downregulated Na,K-ATPase activity in cultured proximal tubule cells. The time course study revealed that EIPA (10(-4) M) significantly decreased Na,K-ATPase alpha- and alpha-mRNA abundance within 4 hr and suppressed Na,K-ATPase alpha- and beta-mRNA levels by 76.3 +/- 4.5% and 85.5 +/- 5.8%, respectively, within 24 hr. The decrease in Na,K-ATPase mRNA was followed by a decrease in Na,K-ATPase activity by 22.5 +/- 10.8% and 48.8 +/- 5.9% within 12 and 24 hr, respectively, which could be reflected by a coordinate decrease in levels of both alpha- and mature beta-protein. The cell viability was not affected until 20 hr of EIPA treatment, when an increase in LDH release and cell detachment was observed. Because EIPA rapidly decreased intracellular pH (pHi) to 6.7 within 2 hr and raising pHi to 6.6 by metabolic acidosis could not elicit changes in Na,K-ATPase activity, EIPA-induced downregulation of Na,K-ATPase should not be mediated through H+. In view of the time course of EIPA effects on Na,K-ATPase subunit mRNA, protein, activity and cell toxicity, the cytotoxic effect is likely resulted from a decrease in Na,K-ATPase activity. Take together, we conclude that EIPA induces downregulation of Na,K-ATPase expression via both pre- and post-translational mechanisms, which confers cytotoxic effects on proximal tubule cells.

Acidosis↗

PubMed1998

The amiloride-sensitive epithelial sodium channel alpha-subunit is transcriptionally down-regulated in rat parotid cells by the extracellular signal-regulated protein kinase pathway.

Previous studies have shown that an inducible Raf-1 kinase protein, DeltaRaf-1:ER, activates the mitogen-activated protein kinase/extracellular signal-regulated protein kinase (ERK)-signaling pathway, which is required for the transformation of the rat salivary epithelial cell line, Pa-4. Differential display polymerase chain reaction was employed to search for mRNAs repressed by DeltaRaf-1:ER activation. Through this approach, the gene encoding the alpha-subunit of the amiloride-sensitive epithelial sodium channel (alpha-ENaC) was identified as a target of activated Raf-1 kinases. alpha-ENaC down-regulation could also be seen in cells treated with 12-O-tetradecanoyl-1-phorbol-13-acetate (TPA), indicating that the repression of steady-state alpha-ENaC mRNA level was dependent upon the activity of protein kinase C, the target of TPA, as well. Pretreatment of cells with a specific inhibitor of the ERK kinase pathway, PD 98059, markedly abolished the down-regulation of alpha-ENaC expression, consistent with the hypothesis that the ERK kinase-signaling pathway is involved in TPA-mediated repression. Moreover, through the use of transient transfection assays with alpha-ENaC-reporter and activated Raf expression construct(s), we provide the first evidence that activation of the ERK pathway down-regulates alpha-ENaC expression at the transcriptional level. Elucidating the molecular programming that modulates the expression of the alpha-subunit may provide new insights into the modulation of sodium reabsorption across epithelia.

Animals↗

PubMed1998

Development and evaluation on transdermal delivery of enoxacin via chemical enhancers and physical iontophoresis.

Iontophoresis and enhancers were performed to enhance percutaneous absorption of enoxacin so as to compare the enhancement between these two enhancing methods. The cationic surfactant of benzalkonium chloride showed the highest enhancing activity for enoxacin for all pH values of buffer vehicles. The enhancement factor of sodium laurylsulfate showed a dose-dependent property between the range of 0.1% to 3.0% concentration. Nonionic surfactant of Polysorbate 80 did not exhibit any enhancing effect on the percutaneous absorption of enoxacin. The highest enhancement factor of iontophoretic delivery was observed at pH 5.0 solution of anodal iontophoresis for cationic enoxacin. The cathodal iontophoresis of negative molecules and anodal iontophoresis of neutral molecules showed lower enhancing effect for enoxacin. The fact that the skin residuals of enoxacin after iontophoresis showed both tremendous and current density-dependent amounts for cationic enoxacin suggested local skin and soft tissue infections might be treated by this physical enhancement method. Combination of benzalkonium chloride and iontophoresis exerted a synergistic effect for anionic enoxacin in pH 10.0, which was possibly due to the shielding of negative charge in skin and the water molecules carried by chloride.

Administration, Cutaneous↗

PubMed1998

Transcriptional regulation of salivary proline-rich protein gene expression.

Mechanisms governing gene expression and regulation in eukaryotes are remarkably complex. The results from in vivo transgenic and in vitro transfection studies designed to identify cis-element(s) and trans-factor(s) associated with the salivary proline-rich proteins (PRPs) gene expression are utilized as a paradigm to discuss the regulation of salivary-specific gene expression. Particular attention is given to the molecular mechanism(s) underlying the salivary PRP R15 gene regulation. In rodents, the PRPs are selectively expressed in the acinar cells of salivary glands, and are inducible by the beta-agonist isoproterenol as well as by dietary tannins. The results from a series of experiments using chimeric reporter constructs containing different lengths of the R15 distal enhancer region, their mutations, and various expressing constructs are analyzed and discussed. These data suggest that the inducible nuclear orphan receptor NGFI-B may participate in the regulation of salivary acinar cell-specific and inducible expression of the rat R15 gene via three distinct distal NGFI-B sites. Taken together, a model for the induction of R15 gene expression by isoproterenol is proposed. However, the exact molecular basis of this NGFI-B-mediated transactivation of cAMP-regulated R15 expression remains to be established.

Animals↗